Not sure if you've ever seen this before:
http://www.kettlepizza.com/
It's an attachment to either the 18 1/2" or 22 1/2" Weber Kettle.
I just got mine last week and cooked 4 pizzas on it last weekend with a nice crisp crust.
The nice part is that everything that comes with it (unit itself, pizza pan, pizza stone, pizza peel) except the thermometer is made in the USA. I actually spoke with the owner and he said that if he could find a thermometer made in the USA he would use that too, it's just that no one makes them.